Cryptosporidiosis is a disease associated with a protozoan, Cryptosporidium, which has very significant negative economic consequences in livestock, because of the increase in mortality and the delays in growth, the cost of the veterinary care and the treatments that it creates, and also the increase in working time for managing the sick animals.
Cryptosporidiosis also affects humans and can have dramatic consequences in immunodepressed patients, in particular in patients suffering from HIV, and also newborns.
The principal clinical sign associated with cryptosporidiosis is acute diarrhea. The other clinical signs associated with diarrhea are in particular dehydration, intense weakness, a loss of appetite and colic. These various clinical signs can lead to death, in particular of young animals.
Halofuginone is the only medicament which has a marketing authorization in France for the prevention and/or treatment of cryptosporidiosis in calves.
However, not only is the efficacy of halofuginone partial, but it exhibits a certain toxicity, and a risk of cryptosporidia developing resistance to this compound has been reported (see Silverlas et al., Preventive Veterinary Medicine, 2009, 91: 73-84).
Moreover, no medicament is registered for the treatment of cryptosporidiosis in kids and lambs.
In humans, nitazoxanide and paromomycin have been used in the treatment of cryptosporidiosis. However, to date, these molecules have marketing authorizations only in certain countries. For example, they do not have a marketing authorization in France.
Thus, no solution exists that is actually satisfactory for the prevention and/or treatment of cryptosporidiosis.
Chitin and chitosan are biocompatible, biodegradable, nontoxic compounds characterized by a strong negative charge. Chitin and chitosan are used in numerous very varied applications, ranging from food-processing to water treatment, and including analytical techniques, the cosmetics industry and the medical field (see Shahidi et al., Trends in Food Science & Technology, 1999, 10: 37-51).
By virtue of their antibacterial and antifungal properties, chitin and chitosan are in particular used as a preservative and in the manufacture of protective food films.
In the medical field, chitosan is, for example, used as an adjuvant in vaccines, a hemostatic agent, an anticoagulant, an antithrombogenic agent, a matrix for producing tissues (skin, bone, cartilage, liver, nerves, blood vessels), an agent for accelerating the healing of and for treating burns, a support for the transport, immobilization and encapsulation of molecules, such as for the controlled release of medicaments.
For example, Alvarez et al. (European Journal of Pharmaceutical Sciences, 2012, 47: 215-227) have tested, in vitro, the effect of microspheres based on chitosan and on polyvinyl alcohol which contain, as medicament, a complex of diloxanide furoate and cyclodextrins, on the infection of intestinal cells by C. parvum. The authors indicate that the adhesion of the microspheres to the intestinal cells in vitro could make it possible to inhibit the attachment of C. parvum to intestinal cells and serve as a medicament release system. However, the capacity of these microspheres to adhere to intestinal cells after administration in vivo is not demonstrated.
Thus, there is a real need for alternative solutions for preventing and/or treating parasitoses, and in particular cryptosporidiosis. Preferably, these alternative solutions have few or no toxic effects, are based on compounds of natural origin, the innocuousness of which in humans and/or animals is known, and are simple to prepare and use.